Froth-flotation concentration of ores



lustrated as applied to the c Patented May 8, 1928.

UNITED "STATES PATENT OFFICE.

cm PIERCE LEWIS, or nuntmeamn, cann omqm, AssIeNon 'ro 'mnms sar- ARATION NORTH AMERICAN 0F MARYLAND.

COBYPORATION, 01 NEW YORK, N.- Y., A CORPQRATION No Drawing.

This inventionrelates to the frothfiotation concentration of ores, agi is herein ilcentration of what are known to miners and concentrator mill men as oxidized ores. Such ores may be truecarbonates, but are .often partly or largely sulphates, hydroxides, oxides and analogous compounds and usually are quite complex and contain a relatively u large amount of primary gangue slimes, VIZ, slimes present in the ore in its natural state as distinguished from slimes produced by grinding the ore. The invention is well adapted for the concentration of such ores 1n which the values are present as carbonates or as basic hydroxides as well as ores in which the presence of primary gangue slimes makes ordinary flotation treatment ineifective.

According to this. invention the concentration may often be efi'ected without the use of any of the sulphidizing agents, socalled. Not only does this eliminate an expensive operation, but it also, in treating some silver-bearing ores, avoids the falling ofl of silver recovery which almost invariably follows when the step of sulphidization is introduced into the process of. concentration.

It has been found that when certain car-' bonate ores are concentrated byl-froth-flotation in the presence of an or anic sulph-- hydric compound such as a xantliate the tailings are cleaner and the concentrate is richer if a small proportion of a soluble silicate, such as sodium silicate, is present in the pulp. Under these conditions, although soluble silicates have normally no substantially beneficial effect on oxidized;minerals, the recovery of both lead and silver from a lead carbonate ore is often substantially better than has hitherto been obtained. Under the same conditions the recovery 03 copper from an oxidized ore containing a elative ly large amount of primary gangue slimes may approach the recovery of sulphide copper from easily fioatable ores.

A pulp of a lead carbonate silver-bearing ore from the Blacksmith Tunnel of Senator mine, Arizona, adjacent to the Schuylkill mine, in which the lead was in the form of carbonate and sulphate, but which contained practically no lead sulphide, was agita ed fifteen minutes in a subaeration mach e Application filed July 28, 1825. Serial No. 48,080.

silicate 1. pound, all per ton of ore. The

concentrate thus obtained was reagitated five m nutes to yield. a finished concentrate and a middling. The results are shown in the following table Per cent assays Per cent recoveries Per cent weight Ag. (02.) Pb. Ag. Pb.

Other tests indicated that the mother liquor and the xanthate itself were substantial equivalents for use in this process.

Other tests of the same ore from other 'parts of the mine, varying considerably in composition, yielded comparable results. Tests of the tailings from these showed that the lead carbonate had almost completely passed into the concentrate.

Another silver-bearing lead-carbonate ore from the Eureka Nevada district, also almost free from leadsulphide, and containing the lead as carbonate and sulphate, was agitated for fifteen minutes in a subaeration machine with xanthate mother li uor 0.8 pound, sodium silicate 1.3 poun s, and American Tar and Turpentine Cos. crude pine'oil 0.4 pound to yield a rougher concentrate. This concentrate was reagitated with added Water to yield a finished concentrate and a middling. The results are shown in the following table:

Per cent assays Per cent recoveries Per cent weight Ag. (02.) Pb. Ag. Pb.

Heads 100. 3. 95 11. 8 Gone 18. 2 11.7 45. 6 54. 0 70. 4 idd -1 27. 1 2. 7 7.'2 25. 3 16. 6

Tails 54. 7 l. 5 2. 8 20. 7 13. 0

Tests of the tailings showed that the lead carbonate had almost completely passed into the concentrate.

In some cases-it maybe advisable to collect the froth-concentrate in two stages, only adding the soluble silicate after the values recoverable without it have been floated in the form of a froth and separated. Some times the addition of a soluble sulphide has been found advantageous, as in the following test of Silver Dyke mine ore of Montana. The ore was ground and then reground with potassium xanthate 03 pound, pine oil 0.5 pound, both per ton of ore. Water was then added and the pulp agitated for fifteen minutes in a subaeration machine, with removal of the froth, there was then added sodium silicate 0.8 pound, and sodium sulphide 3.5 pounds, both per ton of ore and the further froth formed was removed. The collected froths were then reagitated for five minutes to form a finished concentrate and a middling. The results are shown in the following table:

Recoveries Per cent percentages of copper present in the heads and products.

\Vhere there is no advantage in separating a first froth before adding the soluble silicate, excellent results have been obtained by the procedure of agitating copper ores in the presence of all the mineral-frothing and other flotation agents, including the sodium silicate. The following example illustrates the results obtainable.

A pulp of a highly oxidized ore from K. C. Y. Copper Co. mine, Chloride, Arizona, with a schist gangue, was agitated in a subacration machine for fifteen minutes with potassium Xanthate, 0.9 pound, sodium silicate, 1.5 pounds, and crude pine oil, 0.6 pound, all per ton of ore. The results are shown in the following table:

Assays Recoveries Per cent weight 0:. On. Cu. 0:. Cu.

weight sac 7 sea The procedure of adding the soluble silicate after the separation of such values as are float-able without it, is especially valuable in concentrating certain copper ores, such as those containlng both chalcocite and oxide, or acid-soluble copper. The following example illustrates the results obtainable.

A pulp of Ray Consolidated ore was agitated five minutes in a subaeration machine with potassium xanthate 0.2 pound, and pine oil 0.15 pound, botl. per ton of ore, and

the froth removed to form a first concentrate. The remainder of the pulp was agitated ten minutes with the further addition of sodium. silicate 0.6 pound, and pine oil 0.25 pound, both per ton of ore, and the froth removed to form a second concentrate. The results are shown in the following table from which it will be seen that the major portion of the oxide or acid-soluble copper was recovered in the second concentrate.

In these analyses the oxideco per is separately given but is also include in the general copper analyses, which show the total ores which consists in agitating a pulp of the ore with a xanthate and a soluble silicate under such conditions that a mineral-bearing froth is produced, and separating the froth.

2. The process of concentrating oxidized ores which consists in agitatin a pulp of the ore with an organic sulphhydric compound in the presence of a soluble silicate facilitating the recovery of oxidized metalliferous mineral and a mineral-frothing agent to form a mineral-bearing froth, and sepa rating the froth.

3. The process of concentrating oxidized ores which consists in agitatin a. pulp of the ore with a xanthate and a mineral-frothing agent and a soluble silicate to form a mineral-bearing froth, and separating the froth.

4. The process of concentratin an ore containing a substantial amount 0 primary gangue slime which consists in a itatin a pulp of the ore with a xanthate an a $0111 1e silicate under such conditions that a. mineralbearing froth is produced relatively free from primary gangue slimes and se aratin the froth. p g

5. The process of concentratin an ore containing a substantial amount 0 primary gangue slimes which consists in agitating a pulp of the ore with an organic sulphhydric compound and a mineral-frothing agent in the presence of a soluble silicate facilitating the recovery of oxidized metalliferous mineral to form a mineral-bearingfroth relatively free from primary gangue slimes, and separating the froth.

6. The process of concentrating an ore containing a substantial amount of primary gangue slime which consists in agitating a pulp of the ore with a xanthate and a mineral-frothing agent and a soluble silicate to form a mineral-bearing froth, and separating the froth.

7. The process of concentrating carbonate ores which consists in agitating a pulp of the ore with a xanthate and a mineralfrothing agent so as to produce a mineralbearing froth, separating the froth, further agitating the pulp with further addition of silicate of soda so as to produce a second mineral-bearing froth, and separating the second froth.

8. The process of concentrating oxidized ores which consists in agitating a pulp of the ore with an organic sulphhydric compound and a mineral-frothing agent so as to produce a mineral-bearing froth, separating the froth, further agitating the pulp with the addition of a soluble silicate so as to produce a secondmineral-bearing froth, and separating the second froth.

In testimony whereof, I have afiixed my signature to this specification.

CARL PIERCE LEWIS. 

